OBJECTIVES: 1) Heparin will be investigated as a modifying factor of hepatic regeneration using both single liver and cross-circulation studies. 2) Insulin/glucagon ratios will be altered in portally eviscerated, hepatectomized cross-circulated rats to investigate modifying effects of these portal factors on the action of the initiating factors of hepatic regeneration which arise from non-portal organs. 3) Cultured adult hepatocytes will be used as an essay system for non-portal initiating factors of hepatic regeneration.